Thermal relay



June 3, 1952 E. A. MILLER 2,599,473

THERMAL RELAY Filed Oct. 25, 1949 I6 2c A 7 IO /'A Patented June 3, 1952 umrso PATENT OFFICE 2,599,479;- THERMAL RELAY Edwin August Miller, Fairfisid, o'cmi.

Application October 25, 1949, Serial No. 123,388

2 Ciaiins.

a spring strip actuated by said thermostatic members adgfaceng, its longitudinal center and to provide said differential support with an adjustablemeans. V

a With reference to the accompanying drawing the Figure 1 is a; side elevation of the device illustrati-ng movable parts in one position; Figure 2 .is a similar elevation omitting electrical thermal windingof certainthermostaticstructure and illustrating movable parts in relatively moved position; Figure 3 is a plan view of a thermostatic; member having its, iorward end supported by a base and illustrating theblade member and its support in dotted lines; Figure 4 is a plan view oi switch blade; Figure 5 is a rear elevation of device illustrating terminals of thermostatic members and contact arms supported by an insulation base; and Figure 6 is an enlarged detail-partly incross-section-i v The thermostatic structure of the improved device is capable of. performing many human-like functions with the greatest accuracy and a greater stability under vibratory conditions due to the flexibility of both layers of the top thermostatic iiiembef supporting the spring strip at an intermediate point the said thermostatic member's main fund-tide being to snap over the switch blade and not: to support the blade under tension or ccmpression. I

With particular reference to the accompanying drawing,; the numeral designates a supporting base of Insulation material to which is secured the rear portions of both thermostatic members 2 and 3 and both contact arms 4 and 5, each of said rear portions extending beyond said support I to provide terminals.

Relative y spaced interfacing contacts 6 and 1 are supported, one by each of the arms 4 and 5, respectively, for engagement by either one of the blade contacts 8 or 9. The switch-blade l0, while shown having parallel outside strips II and I2 with relatively aligned spring strip portions [3 and I3A therebetween, may comprise, if desired, two outside spring strips with the holding blade strip therebetween or different arrangement thereof.

2 7 While the thermostatic. members 2 and} are shown as comprising bimetal layers 2A-2B and 3A 3l3, respectively, they of course are not intended to be limited as to the number of such layers-.-

i, V H The Figure 1- illustrates each or the thermostatic members 2 and; as having thermal windings l4 and I5, respectively, butboth or either of such windings 4l 5 may be-dispensed wi-thas illustrated by the Figure 2- as to one of said windings. h a

The thermostatic member 2 is providedwith a downwardly bent extremity l6. which is provided upon its rear and forward sides with notches Il-IB, said notches Isll8 being. relatively. positioned as shown in the Figure 1, or staggered as shcwniii the Figure 2. a i

The bent extremity I6 is ffibvabl between the parallel outside strips II and: 12, the relatively aligned spring strip pcsrticns la and HA having their abutting extremities 13B and we each held within a notch IT or 'l8 of the bent extremity I'B of the thermostatic member 2. a

The rear extrem ty or the switch blade In, as illustrated by th Figure 1, is differentiallyheld by the support 30 carried b'ythe extremity 3130f the thermostatic member: such differential holding means being best illustrated by the Figure 6 as comprising' the headed screw mix the shank of which is iirs't inserted withinan enlarged perforation MB of the 'blade l0 and within the coil spring 00 which ntervene between the blade [0 andthe topsurraee an of the support 3C, the extremity MD or the; screw HIA being secured within the" support to, but the said holding means may be of any similai'stiucture, the screw IDA providing an adjustable means for tightening the tension of the spring )0.

In operation, electrical circuitshaving been established, including the terminals 26, 3D, A and 5A, and electrical current is applied to the extremities -I4A l4 l and ma -i513; of the thermal windings l4 and 15 respectively, of the Figure 1, the resulting heat therefrom will eirpand layer 23 of the thermostatic member 2 and layer 3A of the thermostatic member 3 whereby the extreme portions thereof l6 and 3A of the members 2 and 3, respectively, will be moved in opposite directions to the positions illustrated by the Figure 2, the blade contact 8 breaking with a snap action its engagement with the contact 8 on the arm 4 to engage the blade contact 9 with the contact I on the arm 5. Such snap action of the blade l0, carrying the blade contacts 8 and 9, is due to the spring strip intermediate end portions I33 and I3C (better shown by the Figure 4) pivotally engaged within the notches I! or I8 and there providing pivot points crossing and snapping over the plane of the switch blade ID as the rear extremity of the switch blade I0 is moved downward with the support 30 carried by the extremity 3D of the thermostatic member 3 and thereby causing the free extremity of the blade Ill to instantly move from the stop 6 to the stop I.

The free extremity of the blade [0 having thus been thermostatically moved from its normal position illustrated by the Figure 1 to the operated position illustrated by the Figure 2, a reverse action is had when the thermostatic influence is lowered or removed from the thermostatic members 2 and 3 by which both members 2 and 3 return to their normal positions as illustrated by the Figure 1, they having completed the relays operating cycle. 7

While a single thermal winding M or [5 is shown carried by either one of the thermostatic members 2 or 3, it is to be understood that, within the intent of the invention, there may be more than one thermal winding on each or both of the members 2 or 3, each of such thermal windings being in a, different circuit, one from the other, to provide a wider latitude of control by having a greater or lesser amount of electrical "current passing through either one or both windings.

I claim:

1. A thermal relay snap acting switch device comprising two relatively spaced substantially parallel arms of thermostatic metal strips, each arm having a fixed extremity separately mounted upon a block of insulation material; relatively spaced'stops supported intermediate said arms by said. block; an erect support carried by one of said arms adjacent the free extremity thereof; a switch blade member having one extremity mounted upon said erect support and free to move thereon longitudinally of said blade member and free to move at the other extremity between said stops; a spring strip of which the extreme ends are carried by the said blade extremities, said spring strip being normally bowed below the plane of said blade member as said free extremity of said blade member is in contact with the upper one of said stops, said bowed spring strip at an intermediate portion thereof being cutto provide two separate lengths of said strip; and a bent extremity with which the free end of the other of said thermostatic arms is provided; notches with which the said bent end is provided upon opposite surfaces thereof to receive the cut ends of the said divided spring strip; whereby upon applied heat to said thermostatic arms the free extremity of each arm will be moved in opposite directions thus to co-operate with said longitudinally movable mounting to position said cut ends of said divided spring strip above said plane of said blade member, the said mounted extremity of which is moved downward as the said separate lengths of said divided spring strip snap with respect to said blade member to suddenly move the said free extremity thereof from said upper to the lower of said stops; and a reverse operation of said thermal relay upon the removal of said applied heat from said thermostatic arms.

2. A thermal relay snap acting switch comprisin two relatively spaced substantially parallel arms of laminated thermostatic metal, each arm having a fixed extremity separately mounted upon a base of insulation material; relatively spaced stops supported intermediate said arms by said base; an erect support carried by one of said arms adjacent the free extremity thereof; a switch blade member having one extremity mounted upon said erect support and free to move thereon longitudinally of said blade member and free to move at the other extremity between said stops; said blade member having an opening therethrough; a pair of relatively opposing compression members within said opening, each of said compression members having an end carried by an extremity of said blade member, and an opposite end engaged within a notch provided therefor upon a bent extremity with which the free end of the other of said thermostatic arms is provided; said notches being normally positioned out of the plane of said blade member as said other extremity of said blade member is in contact with one of said spaced stops; whereby upon applied heat to one of said thermostatic arms to move its free extremity thus to co-operate with said longitudinally movable mounting and another of said thermostatic arms to position said notch engaged extremities of said compression members from one to the other side of the said plane of said blade member, the said mounted extremity of which is moved in a direction opposite to that of said notch engaged ends, as the said compression members move overcenter with respect to the plane of said blade member to suddenly snap-actingly move the said free extremity thereof from one to the other of said spaced stops; and a reverse operation of said thermal relay upon the lowering or removal of said applied heat from the said one of said thermostatic arms.

EDWIN AUGUST MILLER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,170,748 Eaton Aug. 22, 1939 2,189,996 Riche Feb. 13, 1940 2,332,911 Hausler Oct. 26, 1943 2,340,877 Hausler Feb. 8, 1944 

